A pick and place device is a device that is used to pick up an object from a first station and thereafter to place or release the object in a second station. Pick and place devices are typically used in various semiconductor manufacturing processes, such as die bonding and die sorting.
After a semiconductor wafer has been fabricated, the semiconductor wafer is usually mounted onto an adhesive film such as Mylar film, and subsequently singulated into individual semiconductor dice. The semiconductor dice may be tested either before or after singulation, in order to generate information for completing a wafer map containing characteristics of each semiconductor die together with its position in the wafer. The semiconductor dice may then be sorted based on the wafer map generated. A die sorting process may involve sorting good dice from defective dice, or sorting dice such as light-emitting diodes (LEDs) according to their electrical properties, light intensity, and frequency.
A pick and place device may be used to sort the semiconductor dice. A pick arm comprising a pick head is used to pick up a semiconductor die and transfer it to an appropriate bin. The die sorting process generally requires the pick head to be accurately positioned with respect to the semiconductor die to be picked up, or the location or bin where the semiconductor die is to be placed. However, pick and place devices are often operated for long hours at high transfer speeds, which may cause the mechanical parts in the pick arms to expand due the heat generated. The thermal expansion of the pick arm would cause its pick head to shift from its original position such that its positioning is no longer accurate, thus resulting in errors during pick-and-place operations.
During a die bonding process, a semiconductor die is mounted onto a substrate. The substrate is transported to a dispensing station where adhesive is applied onto bonding locations on the substrate, and thereafter the substrate is moved to a bonding station. At the bonding station, a semiconductor wafer comprising separated semiconductor dice adhering to an adhesive film clamped in a frame are provided on a wafer table. A pick and place device picks up each semiconductor die and places it onto a respective bonding location on the substrate. The picking and removal of the semiconductor dice from the adhesive film and the placing of the semiconductor dice onto the substrate, are processes that require high precision, especially as sizes of semiconductor dice and and their bonding locations become smaller with technological advancements. As explained above, pick and place devices are often operated for long hours at high transfer speeds, which may cause their pick arms to expand due the heat generated. The thermal expansion of the pick arm would cause its the pick head to shift from its position and resulting in errors.